X-ray fluorescence mercury determination using cation selective membranes at sub-ppb levels

In the present work a method for the determination of mercury at trace levels by energy dispersive X-ray fluorescence (EDXRF) is introduced. Mercury ions were concentrated on cation selective membranes that have been prepared on Mylar^® thin film substrate, immobilized on plastic cups. The produced membranes were immersed in water solutions containing low concentrations of mercury. The membranes were left to equilibrate in 1000 mL of mercury solutions and were analyzed by EDXRF. The effects of various experimental parameters were examined. Minimum detection limits of pg mL⁻¹ (ppt) (0.069 ng mL⁻¹ for ASTM Type I water and 0.064 ng mL⁻¹ for seawater) and good linearity were achieved.